There has been used a large-capacity storage system including a plurality of connected disk enclosures in each of which a plurality of storages, such as disks, are received. The disk enclosure is one of a storage apparatus. In addition, various techniques of reducing the power consumption of such a storage system have been proposed because operating all of storages included in the storage system at all times entails higher power cost.
For example, according to an existing technique, a Serial Attached SCSI (SAS) repeater chip is mounted on a storage system, an higher-level control apparatus connected to the storage system controls power supply to storages received in each disk enclosure using an out-of-band (OOB) sequence, thus reducing the power consumption of the storage system. Recently, there has been proposed a storage system that is mounted with no SAS repeater chip in order to support SAS 1.1 or SAS 2.0.
In recent years, however, storage systems are expected to reduce the power consumption by performing power supply control without using repeater chips.